diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 66cd718b70..5dfaeeed5f 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -270,9 +270,6 @@ static void pc_q35_init(MachineState *machine)
     for (i = 0; i < GSI_NUM_PINS; i++) {
         qdev_connect_gpio_out_named(lpc_dev, ICH9_GPIO_GSI, i, x86ms->gsi[i]);
     }
-    pci_bus_irqs(host_bus, ich9_lpc_set_irq, ich9_lpc, ICH9_LPC_NB_PIRQS);
-    pci_bus_map_irqs(host_bus, ich9_lpc_map_irq);
-    pci_bus_set_route_irq_fn(host_bus, ich9_route_intx_pin_to_irq);
     isa_bus = ich9_lpc->isa_bus;
 
     if (x86ms->pic == ON_OFF_AUTO_ON || x86ms->pic == ON_OFF_AUTO_AUTO) {
diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
index 1fba3c210c..54a8839cd2 100644
--- a/hw/isa/lpc_ich9.c
+++ b/hw/isa/lpc_ich9.c
@@ -259,7 +259,7 @@ static void ich9_lpc_update_apic(ICH9LPCState *lpc, int gsi)
     qemu_set_irq(lpc->gsi[gsi], level);
 }
 
-void ich9_lpc_set_irq(void *opaque, int pirq, int level)
+static void ich9_lpc_set_irq(void *opaque, int pirq, int level)
 {
     ICH9LPCState *lpc = opaque;
     int pic_irq, pic_dis;
@@ -275,7 +275,7 @@ void ich9_lpc_set_irq(void *opaque, int pirq, int level)
 /* return the pirq number (PIRQ[A-H]:0-7) corresponding to
  * a given device irq pin.
  */
-int ich9_lpc_map_irq(PCIDevice *pci_dev, int intx)
+static int ich9_lpc_map_irq(PCIDevice *pci_dev, int intx)
 {
     BusState *bus = qdev_get_parent_bus(&pci_dev->qdev);
     PCIBus *pci_bus = PCI_BUS(bus);
@@ -286,7 +286,7 @@ int ich9_lpc_map_irq(PCIDevice *pci_dev, int intx)
     return lpc->irr[PCI_SLOT(pci_dev->devfn)][intx];
 }
 
-PCIINTxRoute ich9_route_intx_pin_to_irq(void *opaque, int pirq_pin)
+static PCIINTxRoute ich9_route_intx_pin_to_irq(void *opaque, int pirq_pin)
 {
     ICH9LPCState *lpc = opaque;
     PCIINTxRoute route;
@@ -680,6 +680,7 @@ static void ich9_lpc_realize(PCIDevice *d, Error **errp)
 {
     ICH9LPCState *lpc = ICH9_LPC_DEVICE(d);
     DeviceState *dev = DEVICE(d);
+    PCIBus *pci_bus = pci_get_bus(d);
     ISABus *isa_bus;
 
     if ((lpc->smi_host_features & BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT)) &&
@@ -728,6 +729,10 @@ static void ich9_lpc_realize(PCIDevice *d, Error **errp)
     isa_bus_irqs(isa_bus, lpc->gsi);
 
     i8257_dma_init(isa_bus, 0);
+
+    pci_bus_irqs(pci_bus, ich9_lpc_set_irq, d, ICH9_LPC_NB_PIRQS);
+    pci_bus_map_irqs(pci_bus, ich9_lpc_map_irq);
+    pci_bus_set_route_irq_fn(pci_bus, ich9_route_intx_pin_to_irq);
 }
 
 static bool ich9_rst_cnt_needed(void *opaque)
diff --git a/include/hw/i386/ich9.h b/include/hw/i386/ich9.h
index 36e0ccd16a..921e4c7ef6 100644
--- a/include/hw/i386/ich9.h
+++ b/include/hw/i386/ich9.h
@@ -9,9 +9,6 @@
 #include "hw/acpi/ich9.h"
 #include "qom/object.h"
 
-void ich9_lpc_set_irq(void *opaque, int irq_num, int level);
-int ich9_lpc_map_irq(PCIDevice *pci_dev, int intx);
-PCIINTxRoute ich9_route_intx_pin_to_irq(void *opaque, int pirq_pin);
 void ich9_lpc_pm_init(PCIDevice *pci_lpc, bool smm_enabled);
 I2CBus *ich9_smb_init(PCIBus *bus, int devfn, uint32_t smb_io_base);